A recurrence transit occurs when two planets which held a certain relationship relative to each other in a chart repeat the exact same alignment again at some point in the future by transit.
For example, if a person was born when Jupiter was exactly 52 degrees from Saturn in the zodiac, then they would have a recurrence transit at some point in the future when Jupiter was again exactly 52 degrees away from Saturn in the zodiac.
In order for it to be a true recurrence transit the two planets must share the exact same phase relationship with each other, so that it is not just a repetition of the distances involved between the two planets, but it is also a repetition their relationship relative to each other as well. That is to say, if Jupiter was 52 degrees from Saturn in the natal chart in the waxing phase of the relationship, then this would be different than if Jupiter was 52 degrees from Saturn in the waning phase of the relationship. Both the distances and the phase relationship involved must be the same for it to be considered a recurrence transit.